Project Summary/Abstract Solid published research now exists on the effects (including reduced utilization and poorer intermediate health outcomes) of cost-sharing and high out-of-pocket (OOP) costs for medications among the elderly. Previously, we developed sensitive new measures of cost-related medication nonadherence for the Medicare Current Beneficiary Survey (MCBS) that were used to quantify improvements in medication access attributable to the 2006 Medicare Part D drug benefit. Nevertheless, medication costs are only 11% of total OOP health spending; yet data on OOP spending for other health services are weak, and data on their affordability are almost non-existent. Elderly beneficiaries, who have modest fixed incomes (median <$25K/year) and substantial healthcare needs and OOP costs, are at risk for economic hardship and underuse of medical care (e.g., going into debt to pay for medical care, failing to seek care for a problem due to cost), which in turn puts their health at risk. Medicare beneficiaries pay roughly $5000 annually in premiums, deductibles, and copayments (based on administrative data for traditional fee-for-service [FFS] enrollees only). A major reason for the lack of data on affordability has been the absence of routine, national, validated measures that evaluate cost burden and cost-related underuse across the Medicare program and over time. Our study will establish an ongoing data resource for examining affordability of care in Medicare. We identified a comprehensive set of measures of patient-reported OOP cost burden (e.g., going into debt to pay medical bills) and cost-related underuse (e.g., forgoing doctor visits or diagnostic tests due to cost) and submitted them to CMS for consideration as new survey items in the annual, national MCBS (n~14000 per year). CMS agreed and is including these items in the MCBS starting in Fall 2017. We will fully analyze the first year of survey results, establishing construct validity, determining risk factors, and comparing prevalence of inaffordability among groups defined by vulnerability (e.g., multiple chronic conditions, low income) and delivery model (traditional FFS vs Medicare managed care). In addition to the new measures, unique strengths of this work will be the rich demographic, health, and insurance data available in the MCBS and our ability to conduct analyses representing the entire Medicare population (i.e., not only those in FFS as in most studies of enrollee spending). Research that excludes the rapidly expanding population in Medicare managed care (33%+) can no longer be adequate. A comprehensive understanding of beneficiary cost burden and cost-related underuse will be essential for monitoring the impact of ongoing changes to the Medicare program. Medicare faces daunting cost pressures, in part due to steeply rising enrollment, and is likely to continue the recent intense experimentation with new ways to reign in program costs. Newer models of care could have profound impacts on affordability, especially for vulnerable populations such as those with multiple chronic conditions. Our exploratory work will lay a foundation for longitudinal research that could guide future policy directions.